Hearing aids are very small and delicate devices and comprise many electronic and metallic components contained in a housing small enough to fit in the ear canal of a human or behind the outer ear. The many electronic and metallic components in combination with the small size of the hearing aid housing impose high design constraints on radio frequency antennas to be used in hearing aids with wireless communication capabilities.
Conventionally, antennas in hearing aids have been used for receiving radio broadcasts or commands from a remote control. Typically, such antennas are designed to fit in the hearing aid housing without special concern with relation to the efficiency of the antenna.
It is known in the art to provide matching circuitry for antennas, and also for antennas used in hearing aids. The matching circuitry may match the impedance of the antenna to the applicable radio or transceiver used and may optimise the effective length of the antenna to the frequency of the radio or transceiver. The matching is typically performed upon initial fitting of the hearing aid, or as disclosed in US2009/0196444, upon replacement of antenna conductors which may vary in for example length from one to another.